Gas turbine engines include a fan having fan blades in front of the engine. The fan may be contained in a hardwall fan containment case. During operation any one of the fan blades may break off from the fan and impact the hardwall fan containment case. This is generally referred to as fan blade-off (FBO). After a turbine engine fan loses a blade, the loads on the fan case rise well above those experienced in normal flight conditions because of the fan imbalance. During engine shut down, which is typically about a few seconds, cracks can propagate rapidly in the hardwall fan case from the damage caused by the impact of the FBO. If the hardwall fan case fails completely, then the consequences for the engine and aircraft could be catastrophic.
The hardwall fan case is generally made of titanium and is designed to stop a broken blade. Titanium or other metal in a hardwall fan case further increase the weight of the gas turbine engine. Thus, there is a need for a lighter hardwall fan case without compromising a structural strength of the fan case to withstand an impact of a FBO.